Several applications exist in which a shaft is to be supported for high-speed rotation. For example, the tail rotor drive shaft of a helicopter or an interconnecting drive shaft of a tilt rotor aircraft are supported in a manner to prevent misalignment of the shaft, yet permit rotation of the shaft at relatively high, e.g., supercritical speeds. Examples for supporting such shafts include bearings and/or hanger brackets. Sometimes, couplings are used to accommodate angular misalignment. In addition, subcritical shafts can be stiff to rotate at speeds below their resonant frequencies to prevent instability. Such rotating shafts experience vibration.